Many language learning programs allow you to access their content online for a fee. However, be sure to check at local universities and your public library, as these places will sometimes have group access to programs like this, making them available to members free of cost.
There are many websites that offer classes online (see Resource section). Some of these classes are free, while others charge a fee. Before you choose a paid program, be sure to fully research it.
Some universities also offer online language classes. The Pennsylvania state university system is planning on offering online Arabic classes at 14 of its universities.
With the spread of Skype and other chat programs, it is now very easy to find Arabic-speaking partners willing to practice their English on you while you practice your Arabic on them. See the Resource section for some possible places to find a study partner. Be careful in choosing your partner, as many of them will speak a dialect of Arabic (Egyptian, Syrian, Moroccan, etc.) that can sometimes be difficult to understand.
Once you have a firmer foundation in the language, an excellent and topical way of practicing Arabic is by watching news programs. Arabic newscasters generally speak in Modern Standard Arabic, so their accent is very clean and easy to understand. There are many different news channels to watch, so check out the Resource section.